The present invention relates to an image reading apparatus which reads images on a document placed on a document holder, or on a document fed onto a document holder by a document feeder, and to an image forming apparatus having such image reading apparatus.
In a copying machine as an image forming apparatus, an image recording device forms an image on a recording material based on image data obtained by an image reading apparatus through reading. When reading images on a document with this image reading apparatus, the image reading apparatus is constituted so that an operator places a document on a document platen as a document holder by positioning the document to a reference plate as a document positioning member, and after that, the operator presses a copy start button to read images on the document on the document platen, for image forming.
A copying machine provided with an automatic document feeding means as a document feeder is arranged so that images on the document fed onto a document platen by the document feeder are read for image forming.
Incidentally, in a conventional copying machine, a reference plate which serves as a reference when placing a document on a document platen is mounted accurately by using an exclusive tool, so that an image on a document placed on a document platen may be read accurately for image forming. In the work of this kind, there have been repeated plural steps on a trial and error basis for adjustment, in each of the plural steps, after a document is positioned to the reference plate to be placed, and images read are recorded on a recording material, the image recorded on the recording material is confirmed visually by a serviceman or an assembly worker, and a position of the reference plate is adjusted based on the results of the confirmation. Therefore, this work has been extremely troublesome, and the time required for the work has been extremely long.
Problems identical to the foregoing are also caused on a copying machine wherein a document positioned to a reference plate to be placed on a document platen is read, and a document fed by an automatic document feeding means is read. Further, in the image reading apparatus stated above, the position where the reference plate is mounted and the position where the automatic document feeding means is mounted are independent from each other. Therefore, the adjustment work stated above is further extensive. In particular, in the case of the automatic document feeding means, not only the mounting position for the automatic document feeding means but also the slip of the conveyance system of the automatic document feeding means are causes, and adjustment work for them is vast.
When the reference plate is inclined to be mounted, images which have been read are inclined, because a document positioned on a document platen along the reference plate is inclined. Even in the case where an automatic document feeding apparatus which feeds a document automatically and stops it on a document platen without dashing against the reference plate is inclined to be mounted, the document stopped on the document platen is inclined, resulting in inclination on the read image. Even if the automatic document feeding apparatus is fixed correctly, when a document is inclined while it is conveyed, the read image is also inclined because the document is inclined to be stopped on the document platen. Further, in the case of an apparatus wherein images of a document are read while the document is being moved and conveyed by an automatic document feeding apparatus under the condition that an image reading device is stopped, the read image is distorted if the automatic document feeding apparatus is mounted to be inclined. Namely, in spite of a document which is rectangular, the read image is a parallelogram whose four corners are not at right angles.
With the background stated above, adjustment work for the mounting position for a document positioning member and adjustment work for the mounting positions of a document positioning member and an image reading device and for the slip of a conveyance system of the image reading device need to be simplified for accurate reading of images and accurate image forming.
The first object of the invention is to provide an image reading apparatus for reading a document by positioning the document to a document positioning member on a document holder manually, wherein accurate image forming which is free from inclination can be conducted even when a position of the document positioning member is not adjusted finely.
The second object of the invention is to provide an image reading apparatus which is capable of reading a document by positioning the document to a document positioning member on a document holder manually and is capable of reading a document fed by a document feeder, wherein accurate image forming which is free from inclination and/or distortion can be conducted for both manual positioning of a document and automatic feeding of a document, without requiring fine adjustment for a position of the document positioning member and adjustment of the slip of a conveyance system of the document feeder.
The third object of the invention is to provide an image forming apparatus which is capable of reading a document by positioning the document to a document positioning member on a document holder manually and is capable of reading a document fed by a document feeder for image forming, wherein adjustment for the mounting positions of the document positioning member and adjustment for the slip of a conveyance system of the document feeder are simplified, and accurate image forming which is free from inclination and/or distortion can be conducted.
The first object of the invention can be attained by an image reading apparatus having a document holder on which a document is placed to be positioned to a document positioning member, and an image reading device which reads images of a document placed on the document holder, wherein a correcting device which corrects an image inclination caused by the slip of the mounting position for the document positioning member.
The second object of the invention can be attained by an image reading apparatus having therein a document feeder which feeds automatically a document, a document holder on which a document is placed to be positioned to a document positioning member, an image reading device which can read images on a document even when the document is fed by the document feeder, or the document is placed on the document holder, and a correcting device which corrects an image distortion caused by the slip of conveyance by the document feeder, for the image data obtained by the image reading device through its reading, when the image reading device reads the document fed by the document feeder, and corrects an image inclination caused by the slip of the mounting position for the document positioning member, for the image data obtained by the image reading device through its reading, when the image reading device reads the document placed on the document holder.
The third object of the invention can be attained by an image forming apparatus having therein a document feeder which feeds automatically a document, a document holder on which a document is placed to be positioned to a document positioning member, an image reading device which can read images on a document even when the document is fed by the document feeder, or the document is placed on the document holder, a memory which memorizes inclination information based on an inclination of a feeding direction by the document feeder and inclination information based on the inclination of the document positioning member, a correcting device which corrects an image inclination caused by the slip of conveyance by the document feeder, for the image data obtained by the image reading device through its reading, based on the inclination information based on an inclination of the feeding direction by the document feeder stored in the memory, when the image reading device reads the document fed by the document feeder, and corrects an image inclination caused by the slip of the mounting position for the document positioning member, for the image data obtained by the image reading device through its reading, based on the inclination information based on the inclination of the document positioning member stored in the memory, when the image reading device reads images on the document placed on the document holder, an image recording device which records images on a recording material based on image data obtained by the image reading device through its reading, and a detecting means which detects conveyance slip information concerning the slip in the direction of conveyance of a document by the document feeder and document positioning member slip information concerning the slip of the mounting position for the document positioning member, wherein the memory stores the prescribed image information, the detecting means detects the conveyance slip information and/or the document positioning member slip information, based on image data obtained by the image reading device through its reading of the recording material on which an image is recorded by the image recording device based on the prescribed image information stored in the memory, and the conveyance slip information and/or the document positioning member slip information detected by the detecting means is stored in the memory.
Further, one of the above objects of the invention can be attained by any one of the following structures (1) through (5).
(1) An image reading apparatus includes: a document holder on which a document is placed; a document positioning member, wherein the document is positioned on the document holder according to the document positioning member; an image reading device for reading an image of the document positioned on the document holder; and a correcting device for correcting an inclination of the image read by the image reading device according to an inclination of the document positioning member, wherein the inclination of the document positioning member is an inclination on the document holder for a primary scanning direction.
(2) An image reading apparatus includes: a document holder on which a document is placed; a document feeder for feeding the document in a feeding direction and stopping the document on the document holder; an image reading device for reading an image of the document stopped on the document holder, wherein the image reading device moves to a sub-scanning direction so as to read the image; and a correcting device for correcting an inclination of the image read by the image reading device according to an inclination of the feeding direction by the document feeder, wherein the inclination of the feeding direction is an inclination on the document holder for the sub-scanning direction.
(3) An image forming apparatus includes: a document holder on which a document is placed; a document positioning member, wherein the document is positioned on the document holder according to the document positioning member; an image reading device for reading an image of the document positioned on the document holder; a correcting device for correcting an inclination of the image read by the image reading device according to an inclination of the document positioning member, wherein the inclination of the document positioning member is an inclination on the document holder for a primary scanning direction; and an image recording device for recording the image corrected by the correcting device on a recording material.
(4) An image forming apparatus includes: a document holder on which a document is placed; a document feeder for feeding the document and stopping the document on the document holder; an image reading device for reading an image of the document stopped on the document holder, wherein the image reading device moves to a sub-scanning direction so as to read the image; a correcting device for correcting an inclination of the image read by the image reading device according to an inclination of the feeding direction by the document feeder, wherein the inclination of the feeding direction is an inclination on the document holder for the sub-scanning direction; and an image recording device for recording the image corrected by the correcting device on a recording material.
(5) An image reading apparatus includes: a document feeder for feeding a document to an image reading position; an image reading device for reading an image of the document being fed by the document feeder at the image reading position; and a correcting device for correcting a distortion of the image read by the image reading device.